Systematical Synthesis of Distamycin Analogues and Their Interaction with Herring Sperm DNA

A simple procedure for the systematical synthesis of eight distamycin analogues containing N‐methylpyrrole (Py) and N‐methylimidazole (Im) has been developed by a chloroform reaction and DCC coupling reaction without amino protection and deprotection, and the interaction of the analogues with Herring Sperm DNA was investigated by fluorescence spectroscopy.     

Synthesis and Structure of a New Dinuclear Molybdenum(Ⅰ)Compound with Cyclohexanthiolate Ligand,[Mo_2(SC_6H_(11)_2(CO)_8]

<正>Molybdenum( I )-compound [Mo2(SC6H11)2(CO)8] 1, crystallizes in monoclinic, space group P21/c with a = 9.5863(9), b = 9.4469(9), c = 13.869(1) A, β = 99.697(2)°, V= 1238.1(2) A3, Z = 2,DC= 1.734 g/cm3, μ = 12.23 cm-1 and F(000) = 644. The finalR = 0.0455 and wR = 0.1159 for 1590 observed reflections with I> 2σ(I). 1 possesses a rhombic bimetallic core MoS2Mo with the Mo-Mo bond length of 2.975(1) and Mo-S of 2.485(2) A.     

高吸收ZnSe多晶无镜光学双稳的实验观测

本文对具高吸收的ZnSe多晶材料的增加吸收型光学双稳性进行了实验观测,发现在介质的吸收远高于过去提出的理论判据时,仍能获得双稳输出,并测定了阈值开关功率与光斑尺寸及样品厚度的关系.采用分层模型分析实验结果,定性地解释了实验现象.     

Characterization of coal oil using three-dimensional excitation and emission matrix fluorescence spectroscopy

Three-dimensional （3D） excitation-emission matrix （EEM） fluorescence spectroscopy is applied to characterize the coal oil. The results show that the 3D fluorescence spectra of coal oil in aqueous solution mainly have one broad peak. This peak is identified at the excitation/emission wavelengths of 270/290 nm. The relation between the fluorescence intensity and the concentration of coal oil is also studied. When the concentration lies between 2 - 2000 ppm, the relation between the fluorescence intensity and the concentration of coal oil is well linear. The nature of solvents significantly affects the EEM fluorescence of coal oil.     

浅谈高等教育心理学在大学物理实验教学中的应用——在牛顿环实验中的尝试

随着现代教育的发展,关注大学生的学习心理研究,提高全体学生的学习效率和效果,教育心理学逐步走入课堂,越来越被教育工作者所重视。许多教师广泛采用教育心理学的原理和理论结构来指导自己的教学实践,并且取得了令人满意的成效。本文采用理论联系实际的方法,对高等教育心理学在牛顿环实验教学中的应用进行了有益探索。     

Structures and stability of N13 cluster

Quantum chemical studies for the nine N₁₃ isomers with low spin were carried out at the UHF/6-31G*, UB3LYP/6-31G* and UMP2/6-311G* levels of theory. The most stable N₁₃ isomer is structure 1 with C_2v symmetry, which contains two separated pentazole rings connected by three nitrogen atoms. The results show that structures 1, 2, 3, 4 and 5 which are composed of the pentazole ring are more stable than the open chain structure 6 and structures 8 and 9 which contain the four- and six-membered rings. This suggests that the pentazole ring is a fundamental stable structural unit, which is applicable not only for the even-numbered nitrogen clusters, but also for the large odd-numbered clusters.     

Interior C 1, γ-Regularity for Weak Solutions of Nonlinear Second Order Parabolic Systems

The interior C ^{γ, γ/2}-regularity for the first gradient with respect to the space variables of a weak solution to a class of nonlinear second order parabolic systems is proven under the assumption that oscillations of coefficients are controlled by the ellipticity constant.     

Simultaneous determination of nitroaromatic compounds in water using capillary electrophoresis with amperometric detection on an electrode modified with a mesoporous nano‐structured carbon material

In this article, a carbon disk electrode modified with mesoporous carbon material (CMK‐3) was used in CE with amperometric detection system for the simultaneous determination of four types of important nitroaromatic compounds, including 2,4,6‐trinitrotoluene (TNT), 1,3,5‐trinitrobenzene (TNB), 2,4‐dinitrotoluene (DNT) and 1,3‐dinitrobenzene (DNB). Compared with the bare carbon electrode, the CMK‐3 modified electrode greatly improved the sensitivity at a relatively positive detection potential due to its excellent electrocatalytic activities, high conductivity and large effective surface area. The four analytes could be well separated and detected within 480 s. A good linear response was obtained for TNB, DNB, TNT and DNT from 8.4 to 5.0×10³ μg/L, with correlation coefficients higher than 0.9992. And the detection limits were established between 3.0 and 4.7 μg/L for the four investigated nitroaromatic compounds (S/N=3). The CMK‐3‐modified electrode was successfully employed to analyze coking wastewater, tap water and river samples with recoveries in the range of 94.8–109.0%, and RSDs less than 5.0%. The presented results demonstrated that the CMK‐3‐modified carbon electrode used in CE with amperometric detection was of convenient preparation, high sensitivity and good repeatability, which could be employed in the rapid determination of practical samples.